The groundwater travel time along the fastest path of likely radionuclide
transport is a regulatory criterion used to assess the hydrogeologic quality of a high -
level radioactive waste repository. Hydrologists and engineers are limited in their
ability to define with confidence the fastest path, owing to the heterogeneous nature
of geologic materials. Field measurements of hydraulic properties such as in test or
observation wells, are inherently averages of properties at scales smaller than the
scale of the field measurement. As a result of averaging, subscale information is lost
and there is uncertainty in defining the fastest trajectory of groundwater. This scale
problem is explained through a review of the continuum and REV concepts in
groundwater hydrology. The application of hydrodynamic dispersion concepts is
recommended as a means of incorporating the effect of subscale heterogeneity on the
fastest groundwater travel time.
Sources of uncertainties in predicting groundwater travel time are discussed
in the report. The uncertainties are mainly attributed to the heterogeneous nature of
geologic formations. The heterogeneity of geologic materials can, however, be
characterized quantitatively using geostatistical methods. Important statistical
parameters include mean and variance. as well as the spatial correlation structures of
the hydrologic properties within the hydrogeologic system. These parameters may he
obtained from limited data base. Stochastic methods, reviewed and explained in this
report, can take advantage of the geostatistical characterization to predict large -scale
groundwater flow and solute transport. Several examples from recent scientific
literature are provided to illustrate the application of stochastic methods to the
groundwater travel time analysis.
Stochastic methods in subsurface hydrology have only recently been
evaluated under field conditions for a few locations, and validation of the theories is incomplete, especially in unsaturated fractured rocks. Nevertheless, research efforts
should continue to improve the state -of -the art. Geostatistics and stochastic methods
will be valuable tools in addressing the groundwater travel time objective
| Identifer | oai:union.ndltd.org:arizona.edu/oai:arizona.openrepository.com:10150/614214 |
| Date | January 1989 |
| Creators | Yeh, T.-C. Jim, Stephens, Daniel B. |
| Contributors | Department of Hydrology & Water Resources, The University of Arizona |
| Publisher | Department of Hydrology and Water Resources, University of Arizona (Tucson, AZ) |
| Source Sets | University of Arizona |
| Language | en_US |
| Detected Language | English |
| Type | text, Technical Report |
| Source | Provided by the Department of Hydrology and Water Resources. |
| Rights | Copyright © Arizona Board of Regents |
| Relation | Technical Reports on Hydrology and Water Resources, No. 89-010 |
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